1. Technical Field
The present invention relates to an image forming apparatus.
2. Related Art
In an image forming apparatus such as a printer, a copying machine, etc., an image may be outputted with different quality of picture from the desired quality due to deterioration of components along with elapse of time, and calibration for correcting the difference in quality is required.
For the purpose of performing gray balance correction or tone correction as the calibration, the correction is carried out by printing a chart composed of a number of colors, and by comparing it with a reference chart which has been printed in advance, or reading it visually or with a measuring instrument.
Particularly, such a method for correction that a reference pattern and a tone pattern in which density and colors are varied are arranged in parallel and printed, and then, the density is visually judged to perform the correction can be carried out at a low cost, without using the measuring instrument and the reference chart. Therefore, various types of this method have been heretofore proposed.